Final-review fixes per Monty, pre-push. OK'd for 
push. Please see each file's comments.



mysql-test/r/federated.result:
  BUG #19773
      
  Results for multi-table deletes, updates
mysql-test/t/federated.test:
  BUG #19773
      
  Test multi table update and delete. Added drop table to end of previous test.
sql/ha_federated.cc:
  BUG #19773 
      
  Post-review changes, per Monty. 3rd patch, OK'd for push.
  - Added index_read_idx_with_result_set, which uses the result set passed to it
  - Hash by entire connection scheme
  - Protected store_result result set for table scan by adding a method result set
    to index_read_idx and index_read which is passed to index_read_with_result, which
    in turn iterates over the single record via read_next.
    This is a change from having two result sets in the first two patches. 
    This keeps the code clean and avoids the need for yet another result set.
  - Rewrote ::position and ::rnd_pos to store position - if primary key use 
    primary key, if not, use record buffer.
  - Rewrote get_share to store hash with connect string vs. table name
  - delete_row added subtration of "records" by affected->rows
  - Added read_next to handle what rnd_next used to do (converting raw record
     to query and vice versa)
  - Removed many DBUG_PRINT lines
  - Removed memset initialisation since subsequent loop accomplishes
  - Removed un-necessary mysql_free_result lines
sql/ha_federated.h:
   BUG #19773
      
      Fixed "SET " to " SET " to make sure built statements are built with 
      "UPDATE `t1` SET .." instead of "UPDATE `t1`SET"